The breeding of captive fish is mainly performed pursuant to two systems: closed tanks or cages and cages that are open on the sides and on the bottom in order to allow water to pass through the cage.
The first system is more expensive and permits full control of the water inside the cage, including its temperature, cleanliness, nutritional content, oxygen content and other factors. Its contact with the surrounding aquatic mediumxe2x80x94seas or lakesxe2x80x94is made through pipes or tubes whose flow can be regulated in order to maintain all the system variables at their optimum values. For this reason, if due care is taken to inject algae-free water into the system, algae problems are eliminated. The scarcity of oxygen in the cage is overcome by introducing water containing dissolved oxygen into the cage. The elevated temperature within the cage is solved by injecting a controlled quantity of cold water from the surrounding sea or lake bottom to replace an equal quantity of warmer water inside the cage.
In the case of the opened cages, many systems are available to reduce the seaweed bloom and attack the reductions of oxygen and other complications associated with the seaweed bloom. One system covers the cage with a plastic mesh to prevent seaweed from entering the cage. This system is used in combination with a compressor that injects and distributes air into the cage to compensate for the reduction of oxygen in the cage. This system is disadvantageous because it is expensive and causes the fish to be stressed. Another system dismantles and drags the cages to sea zones where seaweed bloom is not present. This system is expensive and produces a high mortality rate in the fish due to the stress involve with moving the cages. An alternative system uses outboard engines to create sea flows in the direction of the seaweed to maintain the seaweed away from the cages. This is only a partial solution and is limited to the direction in which the engine is operating. Another possible system avoids the seaweed by submersing the cages below the surface of the water. This system makes it difficult for the fish in the cages to obtain sufficient food and oxygen.
The reduction of oxygen that is present in the open cages is corrected by the use of air injection. One system injects air through compressors that produce micro-bubbles by means of a ceramic element or the like. This system is expensive and creates bubbles that cause stress to the fish. Another system injects air through porous hoses that distribute oxygen in the seawater. This system is not efficient because it fails to transfer an appropriate amount of oxygen to the sea.
It is known in the art to use different devices for controlling the temperature of water in open fish breeding cages by drawing medium flows of water from deeper cooler or warmer zones to the cages. Because these kinds of devices are directed to the temperature, they are not able to solve the xe2x80x9cbloom of harmful seaweedxe2x80x9d problem or the xe2x80x9clack of dissolved oxygenxe2x80x9d problem.
In the breeding of fish in captivity, in cages located in the sea and lakes, a number of troubles are found in surrounding zones in which are involved biological, physical and chemical factors of the water and oceanographic. The most relevant problems for this business activity are the xe2x80x9cBloom of harmful seaweedxe2x80x9d and the xe2x80x9clack of dissolved oxygen concentration in the water seaxe2x80x9d. The bloom of seaweed is a flowering or explosive increase of microscopic seaweed. The seaweed is highly concentrated in the first six meters of depth and is transported by the sea flow. The seaweed enters into the cages of fish and provokes high rates of fish mortality by entering in their bronchia and preventing them from breathing, resulting in asphyxia. The cause of the bloom of seaweed has a natural, biological, physical and chemical origin, and is determined by oceanographic and weather conditions. The oxygen drops are decreases of the water oxygen concentrations below the minimum levels for fish survival. Lack of oxygen increases with the depth of the water and causes the fish to die from asphyxia. This water phenomenon is the consequence of alterations in the factors involved in water oxygen concentrations due to the change in weather and ocean conditions.
The system of the present invention extracts deep waters, with low concentrations of seaweed to a major flow, carrys it to the surface and produces a water flow dissolving the seaweed concentrations and carrying them far away from the cages on an expansive wave. Likewise, the system injects the surface water, with better oxygen concentrations, towards deep waters which contain fish life but lack of dissolved oxygen concentrations.
Other features and advantages of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings.